1. Field of the Invention
The present invention relates to an optical element, and a method and apparatus for fixedly joining the optical element, and more particularly to an optical element, and a method and apparatus for fixedly joining the optical element capable of reducing deformation of the optical element arranged in a layer structure.
2. Discussion of the Background
In an image forming apparatus using an electrostatic copying method such as a digital copier and a laser printer, a laser beam emitted from a laser light source is polarized by a light deflecting unit to irradiate a previously uniformly charged photoconductor so that an electrostatic latent image is formed on the photoconductor. The electrostatic latent image is developed with toner into a toner image, and the toner image is transferred onto a sheet so that an image is output.
In a case a color image is formed, the image forming apparatus using the electrostatic copying method is configured and controlled as described below. A plurality of photoconductors arranged in a row in a conveyance direction of a sheet are exposed to laser light to form respective latent images on the respective photoconductors. The electrostatic latent images are then developed into toner images in respective colors (yellow, magenta, cyan, and black) corresponding to the photoconductors. The toner images are transferred onto a sheet so that the toner images are overlaid one after another to finally form a color image. The configuration and control have achieved image forming using a plurality of colors, an increase in image forming speed, and improvement in image quality.
The image forming apparatus having the above configuration and control uses a plurality of optical elements when performing optical scanning to form an electrostatic latent image. Since a large space is required to accommodate the plurality of optical elements, an optical scanning apparatus for performing the optical scanning needs to be enlarged, and the whole image forming apparatus needs to be enlarged, accordingly.
Against the above background, space saving efforts have been made by arranging optical elements such as imaging lenses provided for respective colors into a layer structure.
A background art for arranging the optical elements in a layer structure uses a lens holder for integrally structuring two imaging lenses in a layered arrangement in a sub-scanning direction.
A background method of holding optical elements places a plurality of elongated optical elements one on another with opposite ends supported. One of the optical elements includes a protrusion arranged at a center in a longitudinal direction of the optical element, and the other optical element includes a receiving concavity arranged in a position opposing the protrusion. When the optical elements are placed, the optical elements are positioned by engaging the protrusion with the receiving concavity.